Melissa Vincent uses her iPhone to take a picture of a dragonfly in the Okavango Delta, Botswana. / Elizabeth Weise, USA TODAY

by Elizabeth Weise, USATODAY

by Elizabeth Weise, USATODAY

MAUN, Botswana - The insatiable desire of advertisers to follow potential customers wherever they're headed means that for some people, doing what they love - if they do it well - can can result in a pretty awesome career.

"I never in my wildest dreams thought it would work out this way," Melissa Vincent, 37, says as she takes a shot of a bug in her tent on the Okavango Delta in Botswana. "But it's pretty cool."

Vincent started out just exchanging photos with her sister back in 2011. But Instagram allowed this stay-at-home mom in Hernando, Miss., to tap into a creative side that she hadn't been able to give voice to before.

She fell in love with the possibilities and honed her craft until she had 390,000 followers who loved the photos she posted as "misvincent."

That in turn caused companies like National Geographic and Dos Equis to come calling, asking her to tag along on trips and post photos of what she saw.

An entire ecosystem has come into being around people like Vincent, who have mega-followings on social media. Companies realize that hiring social-networking stars on Instagram, Pinterest or Twitter is a crucial way to reach customers.

With a plugged-in younger generation turning away from traditional ad spaces such as newspapers, broadcast television and magazines in droves, ads need to go where the eyeballs are.

Agencies are springing up to bring the two together. One example is the Mobile Media Lab, created by friends who started posting on Instagram soon after it launched.

In 2011, Anthony Danielle and Brian DiFeo wanted to go to the sold-out Newport Folk Festival. Danielle e-mailed the festival's social-media coordinator and said that in exchange for tickets, he and DiFeo would launch the festival's Instagram account.

Six months later, they were approached by a fashion brand to post photos during New York Fashion Week for $200.

That experience pushed them to launch a creative agency for Instagram and other social-media influencers. Their first client was Nike, Danielle says.

Sometimes, a client comes to them saying it wants a presence on Instagram and needs to find photographers. Other times, the company loves a given photographer and wants the agency to negotiate the contract. Currently, the company has about 200 Instagrammers it works with worldwide, DiFeo says.

That's how Vincent ended up staying at a swanky hotel in New York for a weekend with Dos Equis' mascot, the Most Interesting Man in the World.

"He showed up in a yacht," she says. There were helicopter rides, long-legged models and a lot of great Mexican food. Her side of the bargain was simply to post six photos a day with the hashtag #Staythirsty.

App developers see connecting with people like Vincent as crucial to getting people to buy and use their apps.

"There are over 25,000 photo-editing apps on iTunes," says Janice Ozguc, who created an app called Layrs, which allows mobile photographers to do multilayer editing. "You need to get noticed - how does somebody know that you're even there?"

Her Newton, Mass.-based company hired Vincent because "these super-Instagrammers have a lot of power," she says. "They become brand ambassadors."

All Vincent had to do was use the app and include a line about it on the photos she posted to her Instagram stream.

The ethics and expectations of how these product placements should be dealt with are in flux. For now, most social-media stars don't specifically state that they're being paid.

It's really something that's been around for almost a century, says San Francisco literary agent Ted Weinstein. "There have always been celebrity endorsements. It's just that the range of celebrities has changed. "

Apps didn't even exist when Vincent started out as a cytologist, someone who studies cells. She spent years working in the pathology lab of a Veterans Administration hospital "looking at stuff under the microscope - urine samples, sputum, bodily fluids," she says.

After her sons were born, she stayed at home. Then, in April 2011, she ran across a new app on her iPhone. It was called Instagram, and "I loved it right away," she says.

At about the same time, her sister, Ali Jardine, 41, in California also created an Instagram account.

"We live 3,000 miles apart, so it was just a fun way to keep in touch and see what the other was doing during the day," Jardine says.

The sisters started competing with each other to get the most followers. Vincent's now over 391,406, and Jardine is at 491,354. Numbers like that got them noticed in the Instagram world, which is how app developers started calling.

They both do these gigs now, though they're careful about the products they choose. "I'm not going to get a company that I wouldn't feel comfortable promoting. It's got to be honest and true, or we wouldn't do it," Jardine says.

The Africa trip was one Vincent could get behind. A National Geographic editor who admired her photos on Instagram asked if she'd be interested in going to Botswana to meet Dereck and Beverley Joubert, a couple who make documentaries and preserve African wildlife.

For that two-week trip, she was asked to post five photos each day.

"This is a new type of celebrity," says Greg Sterling, who writes about media and advertising. "Anybody who has a sufficiently large audience will be found by marketing brands who want to disseminate their message or promote themselves via that channel."

But it can't be forced. "Part of why these social-media types are successful is there's some passion for what they're doing. It's not a calculated act; they're not Kim Kardashian," Sterling says.

Vincent certainly isn't acting as she squeals when a pride of lions settles into the shade of the SUV she's sitting in.

"I still can't believe I'm here," she says, leaning out to get a better angle with her iPhone. "Nobody in my town will ever believe I was here."